Sean was playing with his bubble wand. His bubble wand could eject 100 bubbles at once. Half of the bubbles would burst within one minute. 1/4 of the original number of the bubbles would survive for 2 minutes. Only 2% of the original number of bubbles would make it to the end of 3 minutes. All the bubbles would burst at the 4th minute. If Sean blew the bubble wand every minute, how many bubbles were there altogether at the 10th minutes?

so only the last 3 minutes count. All the bubbles in minutes 1-7 have popped.

100 * 1/2 + 100 * 1/4 + 100 * .02 = 77

To find out how many bubbles there were at the 10th minute, we need to track the number of bubbles at each minute and how many would survive.

First, let's break down the information given:

- Initially, Sean ejects 100 bubbles.
- Half of the bubbles burst within 1 minute, so there are 100/2 = 50 bubbles left.
- 1/4 of the original number of bubbles survive for 2 minutes, so there are 50/4 = 12.5 bubbles left. Since we can't have half a bubble, we round down to the nearest whole number, so there are 12 bubbles left.
- Only 2% of the original number of bubbles make it to the end of 3 minutes, so there are 100 * 0.02 = 2 bubbles left.

Since all bubbles burst at the 4th minute, there are no bubbles left after 3 minutes.

Now, let's determine what happens from the 5th minute onward. Since all the bubbles have burst by the 4th minute, we start with 0 bubbles.

At the 5th minute, Sean ejects 100 bubbles, but they all burst immediately, so there are still 0 bubbles.

At the 6th, 7th, 8th, and 9th minutes, Sean ejects 100 bubbles each time, but again, they all burst immediately. So, at each of these minutes, we still have 0 bubbles.

Finally, at the 10th minute, Sean again ejects 100 bubbles, and they all burst immediately. Therefore, there are still 0 bubbles at the 10th minute.

So, altogether, at the 10th minute, there are a total of 0 bubbles.